Network communication is an integral part of many software and hardware applications. Therefore, network problems often impact application behavior. The impact on network communication depends on the nature of the problem. For example, if a local name server is down, Domain Name System (DNS) requests will be sent but no responses will be received. On the other hand, if a firewall at the edge of a corporate network is blocking a Hypertext Transfer Protocol Secure (HTTPS) port, then TCP SYN packets will be seen but not any corresponding SYN/ACK packets.
Since application problems can be the result of many different failures, sometimes in combination, it can often be difficult for a common user, or even a specialist, to ascertain what the cause of a problem is and how to correct it.